1. Field
One or more embodiments described herein relate to an electro-optical device.
2. Description of the Related Art
An electro-optical device has been developed to include organic light-emitting diodes (OLEDs) that emit light according to the intensity of supplied current. In this device, driving transistorsreceives gate voltages corresponding to gray scale data of an image signal. These voltages determine the amount of current supplied to corresponding OLEDs. The luminance of the OLEDs is adjusted by controlling the intensity of current supplied to the OLEDs. The OLEDs may emit light of predetermined colors.
A field effect transistor (FET) is used as the driving transistor of each pixel. The FET has, as an inherent value, a gate voltage (threshold voltage Vth) at which current starts to flow between a source and drain. The current is proportional to a difference between the gate voltage and threshold voltage Vth (proportional to a square of this difference).
The threshold voltages of the driving transistors are irregular. Thus, even when the same gray scale voltage is applied to gates of the driving transistors, the amount of current supplied to respective OLEDs is often different from each other. Consequently, the luminance of light emitted from the OLEDs will differ from each other.